1. Field of the Invention
The present invention relates to a caption information receiving apparatus for extracting and displaying character information from video signals containing multiplexed character information, such as caption information, etc. and more particularly, to a caption information receiving apparatus which makes it easy to replay caption information.
2. Description of the Related Art
There are a variety of systems available for multiplexing and transmitting character and graphic information during the vertical retrace line period of video signals, such as television signals. This type of system includes, for instance, the character information broadcasting system in Japan; the world standard teletext (WST); the extended version of the United Kingdom teletext system; the closed caption system of the U.S.A., etc.
For instance, in the case of the closed caption system in the U.S.A., a caption signal in the form of a digital signal, which is caption information, is carried on the 21st line of the video signal during the vertical retrace line period of video signals. On the receiving side, the digital signal is extracted from the caption signal through a slice process to decode the caption signals.
The caption signal in this case is comprised of a clock run-in (CRI) signal added to the head of the caption signal for synchronizing with a digital signal when it is decoded and a succeeding digital signal. The caption information obtained by decoding the digital signal is principally comprised of the character information to be displayed on a display screen in connection with a picture image.
The digital signal is decoded in this case in a caption information receiving apparatus. The caption information receiving apparatus receives a video signal with a caption signal in the form of a digital signal carried during the vertical retrace line period and extracts the caption signal from the video signal and decodes the caption information from the digital signal representing the caption signal.
On the other hand, when learning a language using the caption information, character information is displayed in synchronization with picture and sound so that it is possible to study the spelling of characters. Further, it is also possible to check words by characters if the user failed to listen. However, words and conversations actually spoken are continuous without pause, and therefore, in learning a language, it may become difficult for a beginner to follow what has been spoken. Therefore, to check a portion of conversation/important words overlooked or failed to be listened to, video signals are once recorded on a magnetic tape using a VCR (video cassette recorder), the magnetic tape is rewound after being recorded and then caption information is displayed again by reproducing information from the magnetic tape. Thus, this practice was inconvenient as there was no adaptability to recheck required information.
A conventional caption information receiving apparatus described above had such inconvenience in that it has no adaptability to recheck required information, as video signals must be recorded on a magnetic tape using VCR to check past speeches or conversations through its caption information as well as past characters or words, while the magnetic tape is rewound after recording and caption information must be replayed by reproducing the information stored on the magnetic tape.